Long-term fate of pharmaceuticals and personal care products in the environment

Pharmaceuticals and personal care products (PPCPs) have recently emerged as a group of potential environmental contaminants of concern. Interest in their occurrence, fate, and toxicity in both terrestrial and aquatic environments has significantly increased. These contaminants can reach the soil through agricultural runoff, the spreading of manure, and the application of treated wastewater to land. In this study, the fate of PPCPs from the wastewater treatment plant to a land application site where PPCPs can transfer from wastewater to soil and groundwater was assessed. Sorption of PPCPs in soils was determined to contribute a better understanding of the fate of PPCPs in soils, and the uptake of these compounds by plants was evaluated. A study on the occurrence of PPCPs at a wastewater treatment plant and in soil and groundwater at a land application site receiving treated wastewater effluent from the plant showed that target compounds (estrone, 17β-estradiol, estriol, 17-ethynylestradiol, triclosan, caffeine, ibuprofen, and ciprofloxacin) can be detected in wastewater, sewage sludge, soil, and groundwater samples from study sites. Samples were collected quarterly over twelve months for wastewater and sludge samples and over nine months for soil and groundwater samples, and determined using HPLC/UV as the primary mode of analysis with qualitative confirmatory analyses using GC/MS on a portion (20%) of the samples. Results indicated that concentrations of PPCPs in wastewater influent, effluent, sludge solid phase, and sludge liquid phase were in the range of non-detect (ND) - 183 g/L, ND-83 g/L, ND-19 g/g, and ND-50 g/L, respectively. Concentrations in soil and groundwater samples were in the range of ND-319 ng/g and ND-1,745 ng/L, respectively. GC/MS data were consistent with the results of HPLC/UV analyses. Overall, data indicate that PPCPs in the wastewater effluent from the WWTP transport both vertically and horizontally in the soil, and eventually reach groundwater following land application of the effluent. A study on sorption of estrogens, triclosan, and caffeine in Ottawa sand and two soil types (a sandy loam and a silt loam) showed that PPCPs can sorb to both sand and soils. Sorption was determined using batch equilibrium method. Freundlich and linear equations were applied to the sorption data in order to obtain sorption isotherms for each test compound and the respective sorption coefficients (Kf, Kd, and log Koc). Resultsindicated that isotherms were generally linear over the range of concentrations tested. Triclosan had the highest values of Kf (231 in the sandy loam and 344 in the silt loam) and Kd (256 in the sandy loam and 282 in the silt loam). The log Koc values for the PPCPs tested varied from 1.85 to 4.30. Desorption tests over 24 h indicated that caffeine had the greatest desorption capacity (>15%) among the compounds in sandy loam soil, while triclosan had the lowest desorption capacity (<1%) in both soil types. Estrone, 17β-estradiol, 17-ethynylestradiol, and triclosan have a strong tendency to sorb to both soils and their corresponding mobility in these soils would be minimal. If persistent enough, estriol and caffeine would have the best potential for groundwater contamination; however, soil conditions would also have to favor leaching for this to occur. The sorption capacity for sorbents was in an order directly related to organic carbon content: silt loam soil > sandy loam soil > sand. The uptake of 17-ethynylestradiol and triclosan from soils by plants was also observed. Pinto beans, Phaseolus vulgaris, were used to determine uptake of both compounds from sand and soil spiked with these compounds once a week for four weeks. Results showed that, in both sand and soil experiments, both 17-ethynylestradiol and triclosan were taken up by bean plants and accumulated in roots more than in leaves. The extent of uptake and accumulation of these compounds in plants grown in sand were higher than in plants grown in soil suggesting that sorption plays a role in limiting the bioavailability of these compounds to plants. In sand, bioconcentration factors (BCFs) of EE2 and triclosan in roots based on dry weight were 1,424 and 11,582, respectively, whereas BCFs in leaves were 55 for EE2 and 85 for triclosan. In soil, the BCF of EE2 decreased from 154 in the first week to 32 in the fourth week while it fluctuated in leaves from 18 – 20. The BCF for triclosan in plants grown in soil increased over time to 12 in roots and 8 in leaves. These results provide information on the uptake potential of PPCPs from soil, which is a potential exposure route for these compounds to terrestrial organisms including humans.

This dissertation won 1st Place in the Texas Tech University Outstanding Thesis and Dissertation Award, Biological Life Sciences, 2011.

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